Initiation of detonation

The transition to detonation occurs as the dislocation tunneling probability approaches unity. While the molecular excitation and dissociation processes are entirely quantum mechanical processes the detonation velocity is accessible through classical means. The detonation velocity, D, is the velocity of the plastic wave where energy dissipation and molecular dissociation take place, D = v. But v = 

U) Vo where vq is the local shear wave speed in the detonation wave. At high shear stress levels, T( r, U) = 1 while Vo is reasonably well approximated by semi-empirical means. Thus, while multi-phonon molecular excitation and dissociation occur in times of 10 s, reaction propagation only occurs at the local shear wave speed in the detonation wave, typically 5 to 10 km/s. 

The unprecedented spatial resolution of the Atomic Force Microscope makes it possible to examine the plastic deformation of shocked or impacted solids at the atomic or molecular levels. At these levels the molecular and lattice behaviors are determined by quantum mechanics. While the AFM is limited to imaging only the surface of the deformed solid, in many if not most shocked or impacted solids the deformation extends throughout the sample. It is necessary to infer the deformation in the interior of the sample from the surface information. In the case of severe deformation as found in shear bands the assumption has been made that the severely distorted surface features extend throughout the similar severely distorted regions in the interior of the solid. This assumption yields reasonable results not accessible by a classical analysis. 

The recent AFM experimental data concerning plastic flow place severe restrictions on possible theoretical accounts of plastic deformation in crystalline solids due to shock or impact. The high spatial resolution of the AFM, = 2 x lO m, reveals substantial plastic deformation in shocked or impacted crystal lattices and molecules. Understanding how this occurs and its effect on plastic flow requires a quantum mechanical description. The semi-permanent lattice deformation has necessitated the development of a deformed lattice potential which, when combined with a quantum mechanical theory of plastic deformation, makes it possible to describe many of the features found in the AFM records. Both theory and the AFM observations indicate that shock and impact are similar shear driven processes that occur at different shear stress levels and time durations. The role of pressure is to provide an applied shear stress sufficient to cause initiation. 

Finally, there is no evidence in the AFM records that plastic flow in crystals occurs by classical physics processes over distances smaller than about 10 to 10  

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A deflagration-detonation transition was first observed in 1985 in a large-scale experiment with an acetylene-air mixture (Moen et al. 1985). More recent investigations (McKay et al. 1988 and Moen et al. 1989) showing that initiation of detonation in a fuel-air mixture by a burning, turbulent, gas jet is possible, provided the jet is large enough. Early indications are that the diameter of the jet must exceed five times the critical tube diameter, that is approximately 65 times the cell size. 

Bjerketvedt, D., O. K. Sonju, and I. O. Moen. 1986. The influence of experimental condition on the re-initiation of detonation across an inert region. Progress in Astronautics and Aeroruiutics. 106 109-130. AIAA Inc., New York. 

Sichel, M. 1977. A simple analysis of blast initiation of detonations. Acta Astronautica. 4 409-424. 

Fig. 2.7. Initiation of detonation in explosives, as shown in a rotating mirror camera.

El Dorado Engineering recommended that the M28 propellant (which is similar to M-9 propellant) not be pumped or handled or allowed to settle in concentrations above 40 percent by weight in water (EDE, 2001b). In this way, inadvertent initiation of detonations would be prevented, and no nondetonation-to-detonation, transition-phase-type reactions would occur in the process if the slurries were shocked. 

A mixture of AN and water forms a low-strength explosive referred to as a slurry or emulsion explosive. Since a mixture of AN and water cannot be detonated by initiation with a moderate detonation strength, to formulate practical slurry explosives nitrate esters such as monomethylamine nitrate, ethylene glycol mononitrate, or ethylamine mononitrate in conjunction with aluminum powder are added as sensitizers that facilitate the initiation of detonation. 

The major chemical components of emulsion explosives are fundamentally the same as those of slurry explosives, as shown in Table 9.4.[i l Instead of the sensitizers used for slurry explosives, a large number of hollow microspheres made of glass or plastics are incorporated to formulate emulsion explosives in order to obtain successive detonation propagation after the initiation of detonation. During detonation propagation into the interior of the explosives, an adiabatic compression results... 

Confinement Effects in Exploding Bridgewire Initiation of Detonation. Title of the paper by R.H.F. Stresau et al, in 4thONRSympDeton (1965), 449-60... 

Paterson also stated (Ref 1, p 471) that in his work the process of transmission has been reduced to its simplest terms. Later expel studies of initiation of detonation suggested, however, that, at least in gases, it... 

Condensed expls, reaction zone) 8) Baum, Stanyukovich Shekhter(1959), 664-753 (Expln in condensed media) 9) A. Vidart MP 42, 83-144 (I960) (Calcn of characteristics of condensed expls) 10) Andreev Belyaev (I960), 193-210 (Deton of condensed expls) 11) L.G. Bolkhovitinov, DoklAkadN 130, 1044-46(1960) (Low-speed deton of liquid expls) 11a) 3rdONRSymp-Deton(1960), pp 469 98, A.W. Campbell et al, "The Shock Initiation of Detonation in Liquid Explosives 12) R.F. Chaiken, JChemPhys 33, 760(1960) in 3rdONRSymp-Deton(1960), pp 304-08 (Comments on hyper-velocity wave in condensed expls 12a) Zel dovich Kompaneets (I960), Chapter 4 (Detonation in condensed expls) 13)... 

A.W. Campbell et al, PhysFluids 4, 498-510(1961) (Shock initiation of deton in liquid expls) 15a) Ibid, pp 511-22(1961) (Shock initiation in solid expls) 16) R.O. Miller, "Estimating Caloric State Behavior in Condensed-Phase Detonations , pp 65-74 in S.S. Penner F.A. Williams, "Detonation and Two-Phase Flow , Academic Press, NY (1962) 16a) R.F. Chaiken, A Kinetic... 

Bolkhovitinov et al, "Initiation of Detonation in Low-Density Trotyl by Air Shock , Ibid, pp 771-77... 

Physics and Chemistry of Explosives Phenomena , which includes, among other items,determinations of initiation of detonation, electrical effects and luminosity accompanying detonation, detonation velocity and temperature of detonation... 

Detonation in real (nonideal) gases and dust clouds] 34) J. Fay, "Initiation of Detonation in 2H2+O2 Mixtures by Uniform Shock Waves , 4thSympCombstn(1952), pp 501-07 35) T.L. Cottrell S. Pater-... 

Accdg to Cook (Ref 32b, p 172), the initiation of deton is fundamentally a heat-balance problem which may be expressed by the following simplified equation ... 

CA 46, 2266(1952 (Initiation of deton in gases. Published theories of deton are reviewed, and some new thoughts on the structure of deton waves and the mechanism of initiation of deton by flames are presented) 14a) F.R. Bowden A.D. Yoffe, "Initiation and Growth of Explosion in Liquids and Solids , Cambridge-UnivPress, England (1952) 14b) J.A. Fay... 

Study of the Initiation of Detonation Waves by Deflagration , USAF Inst of Tech, Wright-Patterson AFB, (Feb, 1954) 16a) B.L. 

Grosse et al, JACS 79, 6341-42(1957) (Initiation to deton of liquid oxygen-liquid methane solns) 21) K.E. Spells D.W. Woodhead, Nature 179, 251-52 (1957) (Initiation of deton by projectile impact)... 

PrRoySoc 246A, 257-68(1958) (Some considerations on mechanism of initiation of detonation in explosives) 30) G.P. 

M.A. Cook etal, TrFaradSoc 56, 1028-38(1960 Promotion of shock initiation of detonation by metallic surfaces) 36a) Andreev Belyaev (i960), 265-68 (Starting impulse and mechanism of initiation) 268-70 (Initiation by heat) 270-73 (Initiation by flame) 273-86 (Initiation by shock or friction) 287-89 (Initiation of expln in projectiles on hitting a target) 36b) J. Favier C. Fauquignon, MP 42, 65-81(1960) (Initiation of expls. and transmission of detonation) 37) D.B. Moore J.C. Rice, Detonation of Secondary Explosives by Lead Azide , SRI (Stanford Research Institute), Poulter Laboratories, Technical Report 004-60(1960) 37a) S.J. Jacobs, AmRocket-... 

August lp6l 38) A. Macek, ChemRevs 62, 53-56(1962) (Initiation of detonation by shock) 38a) J.R. Travis, A.W. Campbell et al, "Shock Initiation of Explosives. 

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